<div class="row">
    <nav class="nav flex-column col-md-3">
        <a class="nav-link active" [routerLink]="['user']">用户管理</a>
        <a class="nav-link" [routerLink]="['product']">产品管理</a>
        <a class="nav-link" [routerLink]="['exit']">退出</a>
      </nav>
      <div class="col-md-9">
        <router-outlet></router-outlet>
      </div>
</div>